The invention relates to a coupling device for radio sets, in particular a portable radio set or car radio set, and a small size tape recorder, in particular a miniature cassette tape recorder which employs a micro-cassette.
A cassette tape recorder with a radio set incorporated therein is known which is provided with a tuner, a tape recorder portion, an amplifier, a loudspeaker and a power supply circuit. Such assembly is adapted to be used in every application, and is also adapted for portable use by the use of an internally housed battery source. As a result of recent developments which enabled a reduction in the cost of manufacturing, it has been extensively accepted in various fields. However, with this assembly, it is necessary to carry the entire assembly even if the user only desires a recording operation.
The present applicant has previously proposed a miniature cassette tape recorder for use with a micro-cassette of a size which is approximately one-quarter that of a conventional compact tape cassette which is usually employed in a casette tape recorder with an assembled radio set. The miniature cassette tape recorder is of a size which can be received in the pocket of a suit or shirt, thereby affording a great convenience to the portable use. An assembly which comprises a detachable combination of such a miniature cassette tape recorder and a radio set, in particular, a portable radio set which is equivalent in function to the above mentioned assembly, is also known.
An electroacoustic unit which comprises a detachable combination of a miniature cassette tape recorder and a portable radio set will be capable of operating as either a radio set or a tape recorder alone when they are coupled together or separated from each other; recording an output signal from the radio set by the tape recorder when they are coupled together; and reproducing an output from the tape recorder by the radio set when they are coupled together. Thus, it affords a convenience of allowing only the small size tape recorder to be carried about when a recording is desired, and additionally enables a high quality recording of an output from the radio set as well as a high fidelity reproduction of an output from a recorded tape by utilizing the amplifier and a high quality performance loudspeaker contained in the radio set, thus eliminating the above mentioned disadvantage of the conventional cassette tape recorder with assembled radio set.
In a conventional cassette tape recorder with an accompanying radio set, the radio portion and the recorder portion are integrally constructed, and therefore, there is provided a mode change-over switch which enables a radio function and a recorder function selectively. An input signal to the recorder is switched as the mode switch is operated. Specifically, when the mode switch is switched to a radio function, an output signal from the radio portion can be reproduced by the loudspeaker, and can also be recorded by the recorder portion. When the mode switch is switched to the recorder function, an output signal from the recorder portion can be reproduced by the loudspeaker or a voice signal from a microphone can be recorded. When recording a signal from the microphone during the record function mode, it is conventional to disable the loudspeaker in order to prevent the occurrence of a howling phenomenon. The mode switch which selects the function in the manner mentioned above can also be incorporated into the electroacoustic unit including a separable radio portion and recorder portion. In both instances, the switching operation is performed by a single switch of a small size, so that it is difficult to discern at a glance in which mode the cassette tape recorder with an accompanying radio set or the electroacoustic unit is placed, with the consequent possibility of inadvertently operating the switch to select a wrong input signal for recording, or picking up environmental noises instead of a voice which is to be recorded. In an attempt to overcome such difficulty, there has been proposed an arrangement which utilizes an automatic tape stop device contained within the cassette tape recorder with a combination of recorder and radio set to reset a tape drive mechanism and to return the mode change-over switch to the radio function automatically when a tape end is reached. However, such an arrangement is extremely complex and requires additional space, which stands in the way of miniaturization of the unit.
On the other hand, when recording an output from the radio portion by the recorder portion or reproducing an output from the recorder portion by the radio portion of the electroacoustic unit of the kind described above, only the recorder portion can be automatically stopped by the action of an automatic stop device at the termination of an intended operation while the radio portion must be deactuated by a manual operation. As a consequence, the user may inadvertently leave the radio portion in its operating state, causing unnecessary power dissipation.
To overcome this difficulty, the present applicant has previously proposed a power supply operating device for the electroacoustic unit of the kind described which permits the radio portion to be operated by an operating member contained within the recorder portion when both portions are coupled together. The power supply operating device comprises a movable contact of a power switch which projects externally of the radio portion so that it can be displaced by a sliding movement of a record/playback button, thus enabling the power switch in the radio portion to be operated by merely operating the recorder portion. In this manner, the entire unit can be easily operated.
However, with the above power supply operating device, it is necessary that the movable contact of the power switch in the radio portion be disposed so as to be engageable with the record/playback button in the recorder portion, thus imposing a severe restriction on the relative positioning of both portions. In addition, when both portions are separated, the movable contact of the power switch is externally exposed though only partially, whereby it is susceptible to deformation or damage.
In arrangement where a cassette tape recorder is incorporated into a car radio set, the recorder in most cases is only capable of a playback operation on a tape which is commercially available or which is specially prepared by the user on a separate tape recorder or cassette tape deck. Thus the user must have a cassette tape recorder for dedicated playback operation which is incorporated into the car radio set, and another cassette tape recorder which is usable elsewhere. The separate tape recorder capable of a recording operation is necessary if a recording is desired either within the car or when a destination is reached.
While a tape recorder capable of a recording within the car is proposed which employs a separate microphone, the limited length of the connection cord for the microphone restricts the distance which the location of the source of an acoustic signal can be picked up by the microphone. If it were possible for a car radio set to intercept a signal emitted by a wireless microphone unit and to pass it to the tape recorder which is assembled therewith for the purpose of recording, the extent within which the recording is available is again limited even though it is slightly increased.
Another problem with the combination of a radio and a recorder is the fact that when an audio signal from the radio is fed to a record input circuit of the tape recorder, the microphone internally housed within the latter is enabled since the recorder is in a record mode, so that extraneous sounds may also be picked up resulting in an unintended and desirable mixed recording. Such an inconvenience could be avoided by providing means which disables the internally housed microphone when the radio and recorder portions are coupled together. However, known means which disable the microphone is constructed to short-circuit the voltage source for the microphone, resulting in a complex and expensive arrangement because of its connection with other circuit arrangements.